1. Field of the Invention
The present invention relates to a supervisory system and method, provided in, for example, a base station (BS or BTS) apparatus in a mobile communication system, for supervising occurrence of a state change and failure of supervised sections performing various processing in the apparatus.
2. Description of the Related Art
An example of this kind of conventional supervising system and method is described in Japanese Patent Publication No. 2845049.
As a supervising system, for example, in the case of supervising a state and failure of a card (hereinafter referred to as supervised card) with various processing functions for a radio base station, there is provided a system in which another card (hereinafter referred to as supervising card) that supervises the supervised cards to control is connected to each supervised card through a bus, and when a state change or failure occurs in each supervised card, the corresponding supervised card spontaneously transmits a message indicative of the state information to the supervising card through the bus.
In another method, the supervising card transmits a request message to collect state information to the supervised card, and the supervised card returns a confirmation message with the state and failure information attached thereto to the supervising card.
Also in the case where supervising cards are comprised of the same two cards alternately set to be currently used and reserved, the supervised card can return the confirmation message to the supervising card, which transmits the request message. However when the supervised card transmits a notice message spontaneously to the supervising card, it is necessary for the supervised card to always recognize which supervising card is currently used to transmit the notice message thereto. Therefore whenever the currently used supervising card and reserved supervising card are switched, a newly used supervising card is notified to all the supervised cards.
However in the conventional apparatus, for example, as a radio base station apparatus, functions and capabilities required for such an apparatus are increased, and the number of cards is also increased that adopt such a redundant construction that the cards are separately set to be currently used and reserved alternately to improve the reliability. As a result, types of cards in the base station apparatus tend to be increased, and the number of total cards in a third generation radio base station reaches almost 100.
Since the supervision notice processing of each card is achieved by software, the conventional method in which transmission and reception of messages is performed synchronously between the supervising card and a plurality of supervised cards provides a high load on a CPU that controls the supervising card.
For example, since the CPU of the supervising card executes processing other than the supervision, when the message indicative of the state change or failure is transmitted from the supervised card during the processing, the CPU should suspend the current processing by interruption processing to execute the supervision processing, thereby providing the high load on the CPU.
Further it is necessary in each supervised card to suppress a resource assigned to the supervision function as much as possible to increase resources assigned to processing originally assigned for the card. However since the supervised cards should negotiate with the supervising card as described above, there is the problem that a ratio of the resource assigned to the supervision function to the entire resource in each supervised card is increased.
An object of the present invention is to provide a supervisory system and method capable of reducing a load on a CPU provided in each card when a supervising card supervises a plurality of supervised cards executing various processing provided in, for example, a base station, and further capable of executing the supervisory control with the load on the CPU reduced even if the number of supervised cards is increased with the expansion of the system.
The object is achieved by a supervisory system in which each of a plurality of supervised devices is provided with a memory, detects occurrence of a state change or failure of the own device, and stores information on the detected state change or failure in the memory, and a current supervising device in the construction that the supervising device is alternately set to be currently used or reserved reads the stored state change or failure information through a bus to supervise the plurality of supervised devices.